1. Field of the Invention
The present invention relates to a method of preparing an (S)-.gamma.-hydroxymethyl-.alpha.-,.beta.-butenolide represented by the following formula: ##STR1##
This compound is useful as a starting material for synthesizing medicines such as Burseran and Isostegane which are antileukemic lignans, Lasalocid A which is an antibiotic, and prostaglandine. 2. Description of the Related Art
The following two conventional methods for synthesizing (S)-.gamma.-hydroxymethyl-.alpha.,.beta.-butenolides are available. These conventional methods, however, have the following problems.
The first method uses a D-ribose as a starting material and synthesizes a subject compound via a ribonolactone, as proposed by P. Camps, et al. (P. Camps et al., Tetrahedron, 38, 2395 (1982)).
According to this method, the product cost is high since ribose as the starting material is expensive.
The second method uses an L-glutamic acid as a starting material and synthesizes a subject compound in six steps in which the starting material is oxidized to the subject compound via a .gamma.-lactone, as proposed by Taniguchi (M. Taniguchi et al., Tetrahedron, 30,3547, (1974)).
The second method which employs a synthesizing process via the .gamma.-lactone has many reaction steps and requires complicated reaction operations. For these reasons, the second method provides a low product yield.